The present invention relates generally to telecommunication systems and more particularly relates to a digital subscriber line access multiplexer (DSLAM) adapted for use with an Ethernet over Very High Speed Digital Subscriber Line (VDSL) transport facility.
There is a growing need among both individuals and enterprises for access to a commonly available, cost effective network that provides speedy, reliable services. There is high demand for a high-speed data network, one with enough bandwidth to enable complex two-way communications. Such an application is possible today if, for example, access is available to a university or a corporation with sufficient finances to build this type of network. But for the average home computer user or small business, access to high speed data networks is expensive or simply impossible. Telephone companies are therefore eager to deliver broadband services to meet this current explosion in demand.
One of the problems is that millions of personal computers have found their place in the home market. Today, PCs can be found in approximately 43% of all United States households and a full 50% of United States teenagers own computers. Virtually every PC sold today is equipped with a modem, enabling communication with the outside world via commercial data networks and the Internet. Currently, people use their PCs to send and receive e-mail, to access online services, to participate in electronic commerce and to browse the Internet. The popularity of the Internet is such that there are an estimated 50 million users around the globe. These figures indicate that in the past few years the personal computer has fueled a dramatic increase in data communications and the corresponding demands on the data networks that carry the traffic.
The Internet serves as a good example of the increased demands that have been placed on data networks. At first, Internet access consisted of text only data transfers. Recently, with the popularity of the World Wide Web (WWW) and the construction of numerous sites with high quality content, coupled with the development of Internet browsers such as Mosaic, Netscape Navigator and Microsoft Explorer, the use of graphics, audio, video and text has surged on the Internet. While graphics, audio and video make for a much more interesting way to view information as opposed to plain text, bandwidth consumption is significantly increased. A simple background picture with accompanying text requires approximately ten times the bandwidth needed by text alone. Real-time audit and streaming video typically need even more bandwidth. Because of the increased requirement for bandwidth, activities such as browsing home pages or downloading graphics, audio and video files can take a frustratingly long period of time. Considering that the multimedia rich World Wide Web accounts for more than one quarter of all Internet traffic, it is easy to see why the demand for bandwidth has outpaced the supply. In addition, the creative community is pushing the envelope by offering audio and full motion video on numerous sites to differentiate themselves from the millions of other sites competing for maximum user hits.
As use of the Internet and online services continues to spread, so does the use of more complex applications, such as interactive video games, telecommuting, business to business communications and video conferencing. These complex applications place severe strains on data networks because of the intensive bandwidth required to deliver data-rich transmissions. For example, a telecommuter who requires computer aided design (CAD) software to be transported over the data network requires a high-bandwidth data pipeline because of the significant size of CAD files. Similarly, a business-to-business transaction in which large database files containing thousands of customer records are exchanged also consumes large amounts of bandwidth. The same is true for users seeking entertainment value from sites offering high quality video and audio. The lack of available bandwidth in today""s data networks is the primary barrier preventing many applications from entering mainstream use. Just as processing power limited the effectiveness of early PCs, bandwidth constraints currently limit the capabilities of today""s modem user
Considering the networking needs of hotel guests, the vast majority of hotel guests are currently forced to use conventional dial up connections at relatively slow data rates. A recent trend in the industry is to try to accommodate guest""s networking needs and their desires for fast Internet access by installing in-room data ports and increasing the capacity of hotel PBX systems and trunk lines. Despite the equipment and facility upgrades, however, the typical PBX cannot support laptop speeds of 56 kbps. The best most PBX systems can handle is 14.4 kbps speeds. Which such slow connectivity, guests quickly become frustrated and the hotel PBX is crippled when stretched to capacity during peak usage hours. Having guests log in over dial up lines, burdens the hotel""s switchboard which may get tied up in knots for hours due to a large number of guests on-line simultaneously. The problem is so bad that, in response, some hotel chains add on extra telephone charges to guests"" bills for local calls longer than a half hour.
The current situation is, therefore, unacceptable in the fast paced environment of today, particularly for the business traveler. The demand for high speed Internet access in hotel guest rooms is growing rapidly, especially when considering most hotel guests are already used to fast Internet access in their homes and offices.
Further, the demand for faster Internet access is growing at hotel meeting and convention facilities. Meeting attendees and tradeshow exhibitors are increasingly requesting fast access service. It is thus expected that in the future, high speed Internet access will become a standard for any hotel catering to the business and convention traveler, in addition to an increasing number of leisure travelers.
Some currently used methods of accessing the Internet are described below, beginning with the common POTS method, Most computer modem users currently access data through the standard telephone network, known as plain old telephone service (POTS). Even when equipped with today""s speediest modems, dial up modems on a POTS network can access data only at a rate of 28.8, 33.6 or 56 Kbps. Dial up modem transmission rates have increased significantly over the last few years, but POTS throughput is ultimately limited to 64 Kbps. While this rate may be acceptable for some limited applications like e-mail, it is a serious bottleneck for more complex transactions, such as telecommuting, video conferencing or full-motion video viewing. To illustrate, full motion video compressed, using the Motion Picture Entertainment Group (MPEG)-2 standard requires a data stream or approximately 6 Mbps, or roughly 208 times the throughput of a 28.8 Kbps modem. Thus, using today""s dial up modems, it would take more than 17 days to capture two hours of video. As bandwidth demands continue to grow, providers search for better ways to offer high speed data access. Further complicating the problem is the need to deliver all these complex services at an affordable price.
Today""s most popular data access method is POTS. But as discussed previously, POTS is limited when it comes to large data transfers. An alternative to POTS currently available is Integrated Services Digital Network (ISDN). In the past few years, ISDN has gained momentum as a high-speed option to POTS. ISDN expands data throughput to 64 or 128 Kbps, both from the network to the user (i.e. enterprise, hotel, home, etc.) and from the user back to the network, and can be technically made available throughout much of the United States and in many other parts of the globe. Similar to POTS, ISDN is a dedicated service, meaning that the user has sole access to the line thus preventing other ISDN users from sharing the same bandwidth. ISDN is considered an affordable alternative, and in general, ISDN is a much better solution for applications such as Web browsing and basic telecommuting. However, like POTS, ISDN is severely limited in applications such as telecommuting with CAD files and full-motion video viewing. The latter requires roughly 39 times the throughput than that provided by ISDN.
Multichannel multipoint distribution service (MMDS), a terrestrial microwave wireless delivery system, and direct broadcast satellite (DBS), such as DirecTv and US Satellite Broadcasting (USSB), are wireless networks. They both deliver high bandwidth data streams to the home, referred to as downstream data, but neither has a return channel through which data is sent back over the network, referred to as upstream data. Although it is a relatively affordable system to deploy for broadcast applications, because it requires no cable wires to be laid, it falls short in interactive access. In order to use a wireless system for something as basic as e-mail, an alternate technology such as a telephone line must be used for the upstream communications.
Another available network delivery system is asymmetric digital subscriber line (ADSL). Offering a downstream capacity of 6 Mbps or more to the home, ADSL has the downstream capacity to handle the most complex data transfers, such as full motion video, as well as an upstream capacity of at least 500 Kbps. However, due to its limitation of upstream bandwidth capacity, it essentially is a single service platform. Also, since it has to overcome the challenge of reusing several thousand feet of existing twisted pair wiring, the electronics required at each end of the cable are complex, and therefore currently very expensive.
Hybrid fiber coax (HFC), a network solution offered by telephone and cable companies, is yet another option for delivering high bandwidth to users that is known in the art. However, HFC has limitations in that HFC networks provide a downstream capacity of approximately 30 Mbps, which can be shared by tip to 500 users. Upstream bandwidth is approximately 5 Mbps and is also shared. A disadvantage with HFC is that shared bandwidth and limited upstream capacity become serious bottlenecks when hundreds of users are simultaneously sending and receiving data on the network, with service increasingly impaired as each user tries to access the network.
It is a current trend among telephone companies around the world to include existing twisted pair copper loops in their next generation broadband access networks. Hybrid Fiber Coax (HFC), a shared access medium well suited to analog and digital broadcast, comes up short when utilized to carry voice telephony, interactive video and high speed data communications at the same time.
Fiber to the home (FTTH) is still prohibitively expensive in the marketplace that is soon to be driven by competition rather than costs. An alternative is a combination of fiber cables feeding neighborhood Optical Network Units (ONUs) and last leg premises connections by existing or new copper. This topology, which can be called fiber to the neighborhood (FTTN), encompasses fiber to the curb (FTTC) with short drops and fiber to the basement (FTTB), serving tall buildings with vertical drops.
One of the enabling technologies for FTTN is very high rate digital subscriber line (VDSL). VDSL is an emerging standard that is currently undergoing discussion in ANSI and ETSI committees. The system transmits high-speed data over short reaches of twisted pair copper telephone lines, with a range of speeds depending upon actual line length.
An important part of a network that supports Ethernet transport over VDSL, is a device adapted to extract the Ethernet signal and couple this signal to a high speed Ethernet connection. It is thus desirable to employ a device with the capability of transmitting and receiving Ethernet over VDSL on a plurality of channels.
Digital Subscriber Line Access Multiplexers (DSLAMs) are known in the art. Currently available DSLAMs, however, do not have the capability of switching a plurality of Ethernet channels. An external device must be employed to perform any desired Ethernet switching. It is thus desirable to have a DSLAM device that incorporates a means of transporting Ethernet frame data over a VDSL transport facility and that incorporates the capability of switching multiple Ethernet channels. In addition, the DSLAM device should have the capability of encoding and decoding Ethernet data as HDLC and encapsulating and extracting the encoded data within VDSL.
The present invention is a digital subscriber line access multiplexer (DSLAM) adapted for use with an Ethernet over Very High Speed Digital Subscriber Line (VDSL) transport facility. The invention utilizes the widely known HDLC communications protocol to encapsulate Ethernet frames for transmission over the VDSL transport facility of the invention. The HDLC protocol formatted VDSL frames are transmitted over a plurality of point to point VDSL links to CPEs where they are subsequently extracted and forwarded as standard Ethernet frames. In the reverse direction, the DSLAM extracts the Ethernet signals from the plurality of CPEs and forwards the Ethernet signals to an integral Ethernet switch.
The VDSL facility transport system comprises an Ethernet to VDSL Customer Premises Equipment (CPE) coupled to a DSL Access Multiplexer (DSLAM) over a VDSL transport facility. The DSLAM is typically located at the curb or before the xe2x80x98last milexe2x80x99 in a subscriber loop. The Ethernet to VDSL CPE functions to receive a 10BaseT Ethernet signal and encapsulate the Ethernet frame into a VDSL frame for transmission over the VDSL facility. Likewise, the Ethernet to VDSL CPE also functions to receive a VDSL signal, extract Ethernet frames therefrom and output them as standard 10BaseT Ethernet signals.
The DSLAM is adapted to receive VDSL frames, extract Ethernet frames therefrom and generate standard Ethernet signals. These standard Ethernet signals are then input to an onboard Ethernet switch. Likewise, the DSLAM is also adapted to receive standard Ethernet frames from a Fast Ethernet input signal and encapsulate them in VDSL frames for transmission over the VDSL facility to a particular CPE.
Both the CPE and DSLAM perform Ethernet encapsulation and extraction whereby the Ethernet frames are stored and forwarded in both directions. Interface circuitry couples the transmit and receive frame data to and from the VDSL channel.
The system comprises means for combining the voice signal from conventional telephone sets with the VDSL data signal. The combined signal is subsequently split at the DLSAM into separate voice and data signals. The VDSL data signal is processed to extract the Ethernet signal which is then input to an Ethernet switch. The voice signal is forwarded to a conventional PBX.
Note that the present invention has applicability to several types of products and applications and is particularly suitable for use with traveling or mobile users, the hospitality market including hotels and motels and Multi Dwelling Units (MDUs).
There is thus provided in accordance with the present invention a Digital Subscriber Line Access Multiplexer (DSLAM) apparatus for use in an Ethernet over a Very high speed Digital Subscriber Line (VDSL) transport facility, the DSLAM connected to a plurality of Customer Premise Equipment (CPE), each CPE connected to the DSLAM via a separate VDSL channel comprising a plurality of channel circuits, each channel circuit corresponding to a channel and comprising an analog front end operative to provide a line interface to a VDSL channel, a VDSL transceiver, an Ethernet bridge adapted to bridge Ethernet transmit and receive signals to and from the VDSL transceiver, respectively, an Ethernet switch having a plurality of ports, each port coupled to a channel circuit, an Ethernet port coupling the Ethernet switch to an external Local Area Network (LAN), a processor and software means operative on the processor for managing and controlling the plurality of channel circuits; the Ethernet switch and the Ethernet port.